The goal of this project is the development of new and improved radiopharmaceuticals labeled with generator-produced radionuclides (Ga-68, Cu-62, Tc-99m) for use in diagnostic nuclear medicine. Major emphasis will be placed on the preparation of tracers for non-invasive evaluation of regional cerebral and myocardial blood flow. New compounds of these elements, possessing properties believed important in achieving the desired in vivo behavior, will be synthesized and characterized at macroscopic concentrations (10-3 - 10-1M) using conventional chemical techniques. Radiolabeled compounds of these nuclides will then be prepared and characterized, with chromatographic techniques being employed to correlate chemistry at the no-carrier-added level with that defined at macroscopic concentrations. The potential of these radiolabeled compounds to serve as useful radiopharmaceuticals will be evaluated by biodistribution studies in rats. Compounds showing adequate uptake in organs of interest will be investigated in greater detail in larger animals (dogs). Suitability for organ imaging will be determined and comparisons with accepted tracers then employed to assess the physiological significance of the images obtained.